The present teachings are predicated upon providing an improved disc brake system for use with vehicles. For example, the disc brake system may be used with almost any vehicle (e.g. car, truck, bus, train, airplane, or the like). Alternatively, the disc brake system may be integrated into assemblies used for manufacturing or other equipment that require a brake such as a lathe, winder for paper products or cloth, amusement park rides, wind turbines, the like, or a combination thereof. However, the present teachings are most suitable for use with a passenger vehicle (i.e. a car, truck, sports utility vehicle, or the like).
Generally, a braking system includes a rotor, a caliper body, a support bracket, an inboard brake pad, and an outboard brake pad located on opposing sides of the rotor. The caliper body further includes a bridge, one or more fingers, and a piston bore. The piston bore houses a piston. The bore has a bore axis that the piston moves along during a brake apply and a brake release. The piston bore may include a fluid inlet, a closed wall, a front opening, and a cylindrical side wall that has a seal groove located near the front opening. Typically, the fluid inlet is located in the closed wall of the piston bore so that when pressure is applied the fluid will flow into the piston bore. During a pressure apply the fluid will push the piston towards the front opening and into contact with a brake pad and then the brake pad into contact with a rotor. The caliper housing moves so that the one or more fingers contact the opposing brake pad and then move the opposing brake pad into contact with the opposing side of the rotor. After a brake release, the brake pads generally move independently of each other, and the brake pads intermittently and randomly contact the rotor resulting in the brake pads, the opposing faces of the rotor, or both possibly being worn unevenly. The uneven wear of the brake pads and/or rotor may be caused during a brake apply, but it is believed that most of the uneven wear of the brake pads, the rotor, or both is caused by the brake pads contacting the rotor during free running; thus, exacerbating any existing disc thickness variation. Any disc thickness variation between the two faces of the rotor, any wobble of the rotor, also called lateral runout (LRO), and any variation on a face of a brake pad, or a combination thereof may continue to increase through use, possibly causing sufficient disc thickness variation (DTV), sufficient brake torque variation (BTV), or both that the operator feels pulsation in the suspension, steering wheel pulsation, brake pedal pulsation, or a combination thereof. If DTV and BTV become severe enough, vibrations may be felt during driving and/or braking so that the vehicle vibrates, which may result in damage to other vehicle components and/or complaints by the vehicle owner. Examples of attempts to control DTV, BTV, or both may be found in U.S. Pat. Nos. 6,234,284; 6,478,122; 6,607,252; and 7,695,075 and U.S. Patent Application Publication Nos. 2002/0169911 and 2009/0101450 all of which are incorporated by reference herein for all purposes. However, some of these systems are very expensive and/or require complex control systems and strategies; thus, it may not be cost effective to implement these systems in existing cars or lower cost cars.
It would be attractive to have a device and/or method that prevents and/or minimizes DTV, BTV, or both over the life of the brake pads, the rotor, or both so that the operator, during braking, does not experience pulsation of the suspension, steering wheel, brake pedal, or a combination thereof. It would be attractive to have a device that extends the life of the brake pads, rotor, or both by maintaining the faces of each respective component in a substantially parallel configuration during a brake-off condition (i.e., running). It would further be attractive to have a system where a rotor does not require replacement at the same time as replacement of the brake pads because DTV of the rotor is minimized during the life of the rotor. What is needed is a device that maintains both brake pads in a parallel relationship and assists in wearing both faces of a rotor, both faces of both brake pads, or both in an equal manner so that the faces of the, rotor and/or brake pads do not vary.